The antigens CD33 and CD66 are expressed on bone marrow derived myeloid cells such as myeloid progenitor cells, monocytes/macrophages and granulocytes (neutrophils, basophils, eosinophils). These cells play key roles in the adaptive and innate immune responses.

Bone marrow mononuclear cells (MNCs) are separated from whole bone marrow by a density gradient centrifugation protocol. Myeloid cells are obtained by positive selection using anti-CD33 and anti-CD66 antibodies and immunomagnetic separation techniques from the MNC population. Isolated cells are characterized by the expression of CD14 and CD66b from flow cytometry prior to cryopreservation.